1. Field of the Invention
The present invention relates to an improved exerciser bike, and more particularly to an improved exerciser bike having two treadle-typed driving mechanisms for driving two rear wheels respectively. Also, the resilient element""s length can be designed to be longer to magnify the restoring force and to prolong the life of the resilient element.
2. Description of the Prior Art
Everybody knows that exercise is beneficial to our health. Traditional exercising devices such as treadmill and stationary exercising bike are indoor and quite tedious. Therefore, outdoor bicycle and tricycle exercises are more and more popular.
Regarding bicycle, not everyone can ride a bicycle. Basically, a tricycle is easier, safer and more stable than a bicycle. For those persons who are not suitable to ride a bicycle or who cannot ride a bicycle (such as kids, elders, weak patients, etc.), riding a tricycle seems to be a better choice for exercising.
A typical tricycle comprises a front wheel and two rear wheels. The two rear wheels are secured on a rear wheel axle and rotated in concert with the rear wheel axle. The conventional tricycle comprise a single rotary driving mechanism for driving the rear wheel axle such that the two rear wheels will be actuated by the single driving mechanism simultaneously. Because there is no any differential gear system in the rear wheel axle, the tricycle may not be turned left or right easily.
Referring to the U.S. Pat. No. 6,010,433, its title is Exerciser Bike Having Two Driving Mechanisms (briefly called the prior art hereafter). The prior art comprises a frame having a front wheel, two rear wheel and two driving means for driving the rear wheel separately. Each driving means includes a ratchet sprocket wheel secured on the rear wheel, a foot support having a middle portion pivotally coupled to the frame at a pivot shaft and having a first end and a second end, a foot pedal secured on the first end of the foot support, and a chain (connected with a spring) engaged on the ratchet sprocket wheel and having a first end secured to the frame and a second end secured to the second end of the foot support.
However, although this prior art can solve the turning problem of the typical tricycle, it causes another design problem. Because the total length of the chain and spring is fixed, if the chain is longer, the spring must be shorter. Thus, the restoring force of the spring will be decreased. If the chain is shorter, the spring must be longer. Thus, the spring (after pulled) is possible to hit the sprocket wheel. Therefore, while designing the length of the chain and the length of the spring. One of both must be sacrificed.
In addition, when the user""s foot presses down the pedal, if the foot support swings a distance, then the spring only extends the same distance. The restoring force of the spring cannot be magnified.
The present invention is provided to obviate the above-described disadvantages of the conventional tricycles.
The primary objective of the present invention is to provide an improved exerciser bike having two treadle-typed driving mechanisms. In which, by utilizing the special design of pulley and wire element, the length of the resilient element can be designed to be longer. So, the restoring force and the life of the spring can be tripled or magnified.
The second objective of the present invention is to provide an improved exerciser bike having two treadle-typed driving mechanisms for driving the rear wheels respectively and separately and for allowing the improved exerciser bike to be easily turned with the rear wheels. Plus, the repeated up-and-down treading exercising is achieved and the user""s body can be kept straight up.
In accordance with the invention, an improved exerciser bike comprises: a frame including a front portion having a front wheel and a handle for steering the front wheel, and including a rear portion having two rear wheel axles; two rear wheels rotatably secured to the rear wheel axles; and two treadle-typed driving means for driving the rear wheels separately; wherein each driving means includes: a one-way ratchet sprocket wheel secured on the rear wheel axles; a foot support having a middle portion pivotally coupled to the frame at a pivot shaft and having a first end and a second end, a pulley being disposed on said second end; a foot pedal secured on the first end of the foot support; and a chain engaged on the ratchet sprocket wheel and having a first end secured to a predetermined point of the foot support and a second end first connected to a wire element which winds on said pulley and then connected to a resilient element and finally secured to an extension rod of the frame, for allowing the rear wheels and the ratchet sprocket wheels to be driven by the foot supports via the chains.